Jumo 222: what's the truth?

[delcyros]

Some more food on timelines:

[+] mid 1940:

RLM selects mass production of JU-288A1 (with side blisters and w/o periscopes) and JU-288A2 (no blisters but periscopes to aim RPC).
Proposed engines: JUMO-222A1 rated 2,000hp on B4 fuel, RLM funds a whole new factory in Vienna for tooling up for this aeroengine
The JU-288A has the following charcteristics:
-3 men crew, pressurized cockpit
-2 RPC turrets (alternative one double and two connected side single turrets)
-internal bombbay for max. 5ts, normal rated 3ts.
-span: 18.29m
-wing area: 54m^2
-MTOW: 15.6t
-range: 3,850km
-cruise speed: 565km/h

[+] mid 1941:
RLM selects mass production of JU-288B.
Proposed engines: JUMO-222A2/B2 rated 2,500hp on B4 fuel,
The JU-288B has the following charcteristics:
-4 men crew, pressurized cockpit
-3 RPC turrets
-internal bombbay for max. 5ts, normal rated 4ts, external hardpoints for 1t bombs or 1.2t drop tank
-span: 20.06m
-wing area: 60m^2
-MTOW: 18.5t
-range: 3,600km
-cruise speed: 540km/h

-ongoing problems of the JUMO-222A2/B2 lead to prototpyes beeing propelled by BMW-801, A/C appears underpowered at this weight by BMW-801.

[+] end of 1941:
Milch initially reduces then cancels orders for production of JUMO-222 and JU-288B, Vienna Ostwerke is given to DB. Milch orders seperation of airframe and aeroengine departments in Junkers.

[+] mid of 1942:
Milch informed Junkers that the JU-288B is not going to be selected for production at all with JUMO-222. Koppenberg and Brandner assure that the JUMO-222 A3/B3 will be by all means cleared for sufficient power and that the preparations went far for mass production. Koppenberg retires. Junkers tries to fit Db-606 and later Db-610 into the airframe. Improvement on JUMO-222 proceed at low pace to JUMO-222A3/B3

[+] mid of 1942:
Junkers FW change the JU-288 to accomodate Db-606 then later Db-610. The resulting Ju-288C has the following characteristics:
-4 men crew, armoured cockpit
-3 RPC turrets
-internal bombbay for max. 5ts, external hardpoints for 1t bombs or 1.2t drop tank
-span: 23.0m
-wing area: 64m^2
-MTOW: 22.8t
-range: 2,500km
-cruise speed: 570km/h


[+] end of 1943:
JUMO returns to the original JUMO-222A1/B1 configuration and changes the supercharger design, leading eventually to the successful JUMO-222 E/F series.
Preparations for poduction of JU-288C with DB-610 starts. At the same time, JU-388K is selected for production. The type has the following characteristics (K2):
-3 men crew pressurized cockpit
-2 x JUMO-222A2/B2 (alternative was BMW-801, DB-603 and JUMO-213)
-1 RPC gun, 3ts internal bomb bay
-span: 22.0m
-wing area: 56m^2
-MTOW: 14.6t.
-range 2800km
-cruise speed: 545km/h
-the plane is based on Ju-188 and Ju-88 designs and has a high degree of common parts with them.

[+] mid 1944:
It is a not well known fact that both, the JU-388K and Ju-288C actually enter production. Next to 2 JU-388K0 prototypes and 10 Ju-388K0 first batch preproduction models an unspecified number of Ju-388K0 from the 2nd batch preproduction was partially completed, one ATG manufcatured JU-388K1 was made when the Jägernotprogramm cancels all deliveries of new bombers and shifts ressources antirely to fighter and recon forces. The few Ju-388K0 produced are rebuildt to photorecon variants in the factory, the JU-388C gets abandoned alltogether with elements offered for the JU-488 prototypes. One may ask what´s the rational in the Ju-388K at all as it returns to the JU-288A specifications with regard to crew size and general aircraft size. This indicates, for me at least, that there was a rational and a need for a bomber with 1940 JU-288A specifications still in 1944. The JU-388K is -compared with the Ju-288- an inferior and less optimized bomber design. For one thing, it kept the obsolete Ju-88 fuselage (with rather limiting space for bombs and fuel tanks) and the Ju-188 tail structure and wings (more complex and weight intensive designs, less space for fuel). The Ju-388K cockpit, however, and RPC instrumentation showed signs of Ju-288 heritage.

 

[davebender]

I don't understand the rational behind Ju-288 airframe period. Why not just use Jumo 222 engines to power existing Do-217 (which then becomes Do-317)? The Dornier airframe was already in production, worked well and performance was similar to Ju-288 airframe when powered by similar engines.

 

[wiking85]

I don't understand the rational behind Ju-288 airframe period. Why not just use Jumo 222 engines to power existing Do-217 (which then becomes Do-317)? The Dornier airframe was already in production, worked well and performance was similar to Ju-288 airframe when powered by similar engines.

That's factually incorrect. First of all the Ju288A could carry two 2500kg bombs internally or just about any combinations of 3000kg otherwise. The Do-217 could only take 3000kg max with a special kit out and anything more was carried externally. Also the 2000hp the Jumo 222s would only give 500hp extra combined above the DB603, which only would translate into a 363 mph top speed; the Ju 288 had a 401 mph top speed. Its even worse when you consider that the Ju 288's cruise speed was 350mph with any bomb load (all that changed was its range), while the cruise speed with the DB603 for the Do-217 was 248 mph, which might rise to 265mph cruise, which is almost 100mph more than the Jumo 222 equipped Do-217.

The Do-217 was an evolutionary design, while the Ju 288 was revolutionary one.

 

[davebender]

I'm under the impression Do-217 bomber airframe was produced in two variants.
2,500kg bomb bay.
4,000kg bomb bay.
Variant with the smaller bomb bay carried additional internal fuel for a greater combat radius.

 

[wiking85]

I'm under the impression Do-217 bomber airframe was produced in two variants.
2,500kg bomb bay.
4,000kg bomb bay.
Variant with the smaller bomb bay carried additional internal fuel for a greater combat radius.

I've never seen any info about that, though I'm aware of multiple variants:
https://en.wikipedia.org/wiki/Dornier_Do_217#Variant_list

Maybe you're thinking of the 317. Otherwise the Do-217 could carry 4000kg with external hard point mounted ordnance, which dropped performance:
https://en.wikipedia.org/wiki/Dornier_Do_217#Specifications_.28Do_217_M-1.29

Armament

4 × 7.92 mm (.312 in) MG 81 machine guns in nose and lateral positions
2 × 13 mm (.51 in) MG 131 machine guns in dorsal and ventral positions
Max Load 4,000 kilograms (8,800 lb) internally externally.
Max Internal Load 3,000 kilograms (6,600 lb).

This max internal load was very rare and only in one configuration with 500kg SD (armor piercing) bombs, which had limited utility.

 

[tomo pauk]

The early 217s (Do-217E-1) was able to carry 2000 kg of bombs internally. For the subsequent bomber variants (starting from the E-2), the bomb bay/bomb carriers were modified, so maximum was 3000 kg of bombs (with shortcoming that CoG was moved rearward with 2800 kg of bombs an more).

added: According to this, SD bombs were 'fargmentary bombs', BTW. The PC and PD bombs were of armor-piercing variety.

 

[wiking85]

Semi-armor piercing actually...which makes sense. Thanks for the resource.

 

[davebender]

What was internal fuel capacity of Ju-288 and Do-217?

 

[tomo pauk]

Do-217 carried 2960 liters of fuel in 'permanent' tanks, up to 1500 L were to be carried in the bomb bay if needed (2x750 L tanks), and 1800 L was capacity of 2 drop tanks (2x900 L). Ju-228 carried 5360 L in 'permanent' tanks, plus 2 x 900 L in drop tanks.

 

[davebender]

The relatively small Me-210 carried 2,420 liters of internal fuel. Seems like Dornier crippled his otherwise good heavy bomber airframe by carrying only 2,960 liters of internal fuel.

 

[tomo pauk]

While it's easy to see that Ju-288 carried far more, the question is what kind of powerplant is needed to lift in the air several tons of fuel and several tons of bombs. The early BMW-801s were fine with lighter weights, not so much when Do-217 was fully bombed- and fueled-up. The Do-217E-2 was able to take off with 2000 kg of bombs and additional fuel tank in the rear bomb bay (3700 L total), and it was not possible to carry the drop tanks in the same time - the maximum take off weight (just under 16,7 tons) was almost reached with that layout of payload. The cruising speed on max TO weight was 435-460 km/h with BMW 801As, at 5km.
So we have both limitations of aircraft (how much of weight was it possible to take aloft) and engine in particular (both for T.O and cruising at meaningful speed).

Of course, I'd like to see some good data on the Do-217 bombers with DB-603A, so we can compare them with data about earlier models.

 

[Denniss]

The Do 217 was also crippled by the dive-bombing requirement. The wing reinforcements may have been a reason for limited space for fuel tanks. It also limited the wing size which in turn led to high wing loading.

 

[DonL]

The Do 217 was never intended as heavy Bomber also the Ju 288.

Both are medium bombers or fast medium bombers, the He 177 was the heavy bomber project.

To my opinion the Do 217 was a very good medium bomber (with Db 603 engines) and the realistic step at 1938/39, it was advanced but a normal step.
The Ju 288 was the try to get two or three steps of development with the next generation a/c and it was to ambitioned for 1938/1939 and much to complex from development and production.

 

[Shortround6]

Maybe Dornier didn't have a lot choice. Do 217 V1 flew over a year before the Me 210 V1 and used 1075hp DB 601 A engines ( not what was wanted but what was available) DO 217 could carry double the bomb load of the Me 210 inside and even more outside.

You want a 3000kg bomb load and only a 522 sq ft wing with 1000-1100hp engines something has to give.

Calling it a heavy bomber doesn't make it one. Even after they made the wing bigger and gave it BMW 801 engines you have a plane with less power than either an A-20 or a B-25, a wing in between the two (about the size of a B-26 wing) and a bomb load (nominal) higher than ether the B-25 or B-26. Weight went between 33,000 lbs "normal" to 36,299lb overload for the Do-217E-2.

 

[davebender]

The one we are currently discussing - Jumo 222. 2,000hp for Jumo 222 which was supposed to begin production during March 1942. Superseded by 2,500hp version a year later. With that engine Do-217 and/or Ju-288 airframe can achieve their full potential.

If the choice is mine to make Ju-288 fuel capacity should earn that airframe the Bomber B contract and Do-217 ends production.

 

[wiking85]

The one we are currently discussing - Jumo 222. 2,000hp for Jumo 222 which was supposed to begin production during March 1942. Superseded by 2,500hp version a year later. With that engine Do-217 and/or Ju-288 airframe can achieve their full potential.

If the choice is mine to make Ju-288 fuel capacity should earn that airframe the Bomber B contract and Do-217 ends production.

The problem that Milch rightly foresaw was that the Ju 288 would supersede all other bombers, save perhaps the He177B, which would put all the other companies out of business and leave Junkers as the only choice for future designs and give his rival, Heinrich Koppenberg, full authority over aviation procurement programs and neuter Milch in his job.

 

[Shortround6]

The one we are currently discussing - Jumo 222. 2,000hp for Jumo 222 which was supposed to begin production during March 1942. Superseded by 2,500hp version a year later. With that engine Do-217 and/or Ju-288 airframe can achieve their full potential.

If the choice is mine to make Ju-288 fuel capacity should earn that airframe the Bomber B contract and Do-217 ends production.

The Do-217 wasn't really in the "bomber B" catagory, it was a low risk back up. First prototype flew Oct 4th 1938 compared to Nov 23 1940 for the first Ju 288 and March 18th 1941 for the Fw 191.

And even if you can wave a magic wand and get working (airworthy) Jumo 222 engines sticking them and another 1800kg of fuel into a Do 217 is going to call for a major re-engineering job.

They built 1541 Do 217 bombers and 364 night fighters before production stopped in June of 1944.
The 36th production Do-217E was delivered in the summer of 1941, several months before the first flight of a Ju 288 with Jumo 222 engines.

 

[stona]

The problem that Milch rightly foresaw was that the Ju 288 would supersede all other bombers, save perhaps the He177B, which would put all the other companies out of business and leave Junkers as the only choice for future designs and give his rival, Heinrich Koppenberg, full authority over aviation procurement programs and neuter Milch in his job.

In what capacity do you imagine that Koppenberg could gain 'full authority over aviation procurement plans' and by implication the generalluftzeugmeister (whoever that might be) whose boss was Reichsmarschall Goering, arguably the second most powerful man in Nazi Germany ?

Milch in particular could always appeal to Goering, he had his ear for most of the war. When he finally fell out with Goering (getting involved in typical Nazi in-fighting and far too late in the war to be relevant to this discussion) he simply went to work with Speer, the Minister of Armaments who really did control all procurement programs and who unlike any other Nazi minister had direct access to Hitler.

It doesn't make sense to me, and contradicts the way I believe the Reich government and aviation industry worked. It was a dictatorship !

Cheers

Steve

 

[wiking85]

In what capacity do you imagine that Koppenberg could gain 'full authority over aviation procurement plans' and by implication the generalluftzeugmeister (whoever that might be) whose boss was Reichsmarschall Goering, arguably the second most powerful man in Nazi Germany ?

Milch in particular could always appeal to Goering, he had his ear for most of the war. When he finally fell out with Goering (getting involved in typical Nazi in-fighting and far too late in the war to be relevant to this discussion) he simply went to work with Speer, the Minister of Armaments who really did control all procurement programs and who unlike any other Nazi minister had direct access to Hitler.

It doesn't make sense to me, and contradicts the way I believe the Reich government and aviation industry worked. It was a dictatorship !

Cheers

Steve

Milch and Goering hated one another, Milch because he had been bribing Goering for years and got him the job at the RLM and because he did all of the actual work, and Goering hated Milch, because Milch actually did all of the work and bragged about it publicly. Milch was sidelined in favor of Udet until his suicide, after which Milch took back over aviation armaments (which is why Milch suddenly started sabotaging the Jumo/Ju 288 project in late 1941, because he suddenly had his authority returned and wanted to reassert himself over weapons projects that were started under Udet). Goering though favored anyone that limited Milch's authority even at this point (late 1941/1942) which is just as Speer is starting to usurp Goering power over the economy (4 year plan office); it wasn't until Speer finally made an alliance with Milch that shut out Goering that Goering's influence over economic matters ended, which happened gradually over 1942; so in 1941-42 Milch was eliminating rivals that Goering might use to undercut him, which he had done since Udet in 1936.
Koppenberg had managed to virtually kill several other projects with the Ju88 program in the meantime (he bragged about sabotaging the Do217 by monopolizing its labor). So while officially Milch had the power, given the competing bureaucracies within the Third Reich which usually issued competing orders, subordinates often had to choose who to obey when they got multiple sets of orders; Koppenberg was on the ascent due to the authority he took from Udet (who was weak and let his underlings make decisions, with the strongest amassing the biggest weapons program resources, like the Ju88, just by force of personality, which incidentally, was how Goering took over the economy from Schacht in 1936. Koppenberg did this with the Ju88 and was pretty much the guy that got his way when issuing orders to people about allocation for labor, raw materials, and machine tools). So when Milch was officially given authority over aviation again after Udet's death he worked to administratively kill his rivals' authority. Koppenberg had managed to become the de facto authority in the allocation of resources in aviation, eventually grabbing over 50% of all available resources for the Ju88 project, which meant that even if Milch issued orders about other projects Koppenberg had the gravitas with the bureaucrats to make sure Milch was disregarded. So Milch had to sabotage Koppenberg by ensuring his projects never came to fruition, so logically couldn't maintain his stranglehold over labor, raw material, and factory resources. Milch successfully played the game and was able to syphon off Koppenberg's power by changing requirements for the Ju 288 project, which meant it could never be produced, so he could swoop in and claim Koppenberg's resources for other projects, rather than let things sit idle. This of course let him reassert his power over the bureaucracy and marginalize Koppenberg to the point he could just be fired, which he was.

https://de.wikipedia.org/wiki/Heinrich_Koppenberg
This also states that Koppenberg diversified his power to direct control over resources too, such as bauxite (used for aluminum) in Norway, becoming the director of mining firms, which gave him direct authority over its allocation. So he was ensuring he couldn't be undercut and could undercut others by controlling the direction of resource allocation. This is the way Nazi Germany worked; bureaucrats seized power from one another via such methods all the time, which ensured a production mess until Speer took over and centralized all authority in his office, which meant the German economy could function rationally instead of in constant inefficient competition. That was Speer's real 'miracle', ensuring that finally the backstabbing was under control and the war effort could be properly supplied.

 

[stona]

I would argue whether Goering hated Milch. They used each other and I could cite dozens of instances when Goering backed Milch, because it suited him. I've never seen any evidence that Goering would favour an industrialist over a senior Luftwaffe officer or member of government.

We certainly can agree that the whole sorry bunch were playing everyone off against each other. The reason Speer was so successful was because he had direct access to Hitler, something even other high ranking Nazis found very threatening. None of them enjoyed that privilege (except Bormann). Nobody in Nazi Germany was going to oppose something that they even suspected might have the direct backing of Hitler, something Speer exploited ruthlessly.

I think the explanation of the Jumo programme, or any other, in terms of personalities is too simplistic. I don't doubt that there may be elements of truth in it, but its not the point of this thread, so I'll duck out

Cheers

Steve